1. Technical Field
The present invention relates to an image optical lens system. More particularly, the present invention relates to a compact image optical lens system applicable to electronic products.
2. Description of Related Art
In recent years, with the popularity of mobile products with camera functionalities, the demand for miniaturizing a photographing system is increasing. The sensor of a conventional photographing camera is typically a CCD (Charge-Coupled Device) or a CMOS (Complementary Metal-Oxide-Semiconductor) sensor. As advanced semiconductor manufacturing technologies have allowed the pixel size of sensors to be reduced and compact photographing systems have gradually evolved toward the field of higher megapixels, there is an increasing demand for compact photographing systems featuring better image quality.
A conventional compact photographing system in a portable electronic product typically utilizes a three-element lens structure. Such a conventional photographing system has a first lens element with positive refractive power, a second lens element with negative refractive power and a third lens element with positive refractive power. The first, second and third lens elements are arranged in this order from an object-side to an image-side. While the three-element lens structure is compact, it is not able to produce high quality images.
Another conventional compact photographing system provides a four-element lens structure. In order to retain high image quality, the smaller chief ray angle of the photographing system is proper corresponding to the image sensor, and provides the best photosensing performance of the image sensor. But, the back focal length and the total track length of the photographing system would be too long for applying to the compact electronic product.
Therefore, a need exists in the art for providing a photographing system for use in a mobile electronic product that has high pixel image sensor, large chief ray angle, and excellent imaging quality without too long total track length.